1. Field of the Invention
The present invention relates to improvements in vacuum dust collection systems which are installed in industrial plants for the removal of dust accumulations, and more specifically to improved dust valves which are utilized as components in the discharge lines of such systems.
2. Description of the Prior Art
Vacuum dust collection systems are widely used in industrial plants where dust accumulations are a reoccurring problem, and for example are regularly installed in iron ore sintering plants, pelletizing plants, stone crushing plants, grain elevators, etc. Such systems conventionally include not only a vacuum-generating means and a dust uptake means, but also a dust discharge line in which are mounted a pair of serially connected dust valves. The dust valves are operable such that the vacuum in the system is never exposed directly to the atmosphere, i.e., the gates within the valve bodies are operated in sequential fashion such that they are never both "open" at the same time.
As is described in detail in Carpentier, U.S. Pat. No. 3,257,045 of June 21, 1966, conventional dust valves used in such vacuum dust collection system discharge lines include internal parts which are subject to wear. More specifically, over long periods of use both the internal valve seat member and the coacting valve flap (door) will become so worn that the sealing engagement therebetween will be no longer obtainable, and this will detract from the operation of the collection system due to vacuum loss. According to this patent the valve seat member is formed as a removable structure (connectable and disconnectable from the supporting structure in the interior of the valve body) and the valve flap (door) may be removable from the supporting valve arm, such that when the valve seat portion of the valve seat member is worn out and/or the coating valve flap is worn out, these structures can be removed from inside of the valve body and replaced. Access to the interior of the valve body is achieved by locating an access opening in one side and then covering this opening with a removable plate which can be sealingly connected to the outside of the valve body by suitable screws (or other fastening means). Thus, by simply removing the plate from the outside of the valve body and illuminating the interior of the valve body through the access opening, a worker can inspect and clean the internal parts and if necessary disconnect, remove and insert a new valve seat member and/or a valve flap. This procedure avoided the wasteful, time consuming and expensive prior art procedures of removing the entire dust valve from the dust collection system discharge line and then either disassembling the valve for replacement of the worn parts or else replacement of the entire valve assembly.
Although the Carpentier dust valves have represented an improvement over earlier valves, the necessity of replacement of the entire valve seat member when the valve seat portion is worn out and/or replacement of the entire dust flap when worn out is a wasteful and expensive procedure, i.e., since much more structure is required to be replaced than simply the portions which wear out.
It is thus an object of the present invention to provide an improved dust valve which utilizes an internal valve seat member and an internal valve door which are not only easily replaceable but which provide a much extended service life as compared to prior art structures.